It is proposed to make a major improvement in the safety of operation of Liquid Encapsulted Czochralski crystal pullers used in the growth of gallium arsenide. The hazard is caused by the presence of finely divided arsenic dust on the inside of the pullers after growth. Some of this is believed to convert to arsine. Operators remove the dust by vacuum cleaning and scrubbing with tissues, and hence are exposed to high levels of toxic and carcinogenic material. The hazard will be eliminated by chemical removal of the arsenic.This will eliminate the health risk to operators, decrease operator turnover (the puller cleaning job is generally detested) and improve the economics of the process by saving the hours spent cleaning. The economics will also be improved by reducing the volume of toxic waste and producing it in a form that is more easily handled.